A vast network of underground tunnels used for warfare and to avoid Israeli airstrikes exists in the Gaza Strip. This infrastructure runs throughout the Gaza Strip and towards Egypt and Israel, and has been developed by Hamas and other Palestinian military organizations to facilitate the storing and shielding of weapons; the gathering and moving of fighters, including for training and communication purposes; the launching of offensive attacks against Israel; and the transportation of Israeli hostages. On several occasions, Palestinian militants have also used this tunnel network, which is colloquially referred to as the Gaza metro, to infiltrate Israel and Egypt while masking their presence and activities within the Gaza Strip itself. According to Iranian military officer Hassan Hassanzadeh, who commanded the Islamic Revolutionary Guard Corps from Tehran, the Gaza Strip's tunnels run for more than 500 kilometres (310 mi) throughout the territory.